Key notes(1) Metabolism is divided into those pathways that are degradative(catabolic)and those that are involved in synthesis. Catabolic pathways often produce energy. Microbes that utilize organic molecules as a source of energy are called heterotrophs Phototrophs obtain energy from light, and lithotrophs(无机营养菌) obtain energy from inorganIc compounds Nutritional typesMetabolism is divided into those pathways that are degradative (catabolic) and those that are involved in synthesis. Catabolic pathways often produce energy. Microbes that utilize organic molecules as a source of energy are called heterotrophs. Phototrophs obtain energy from light, and lithotrophs(无机营养菌) obtain energy from inorganic compounds. Key notes (1) Nutritional types